Magnetic Coupling Mobile Robot

ABSTRACT

A robot including a frame with wheels moves over a highly magnetically permeable support surface and at least one permanent magnet able to interact magnetically with, and couple the robot to, the surface. The permanent magnet is positioned so that one pole grazes the surface and is free to oscillate so that the pole always faces the surface and is a minimum distance from it.

FIELD OF THE INVENTION

The present invention relates to a mobile robot with magnetic coupling.

In some applications in the art, surfaces to be processed or treated invarious ways, for example, to be welded together, may be inspected by arobot provided with wheels allowing the robot to move along the surface.The robot is fitted with probes able to inspect the surface bydetecting, for example, the quality of the process carried out.

When the material of which the surface is made allows it, i.e. when itis ferromagnetic, the robot is coupled magnetically to the surface bymeans of permanent magnets. Thanks to this anchoring system, the robotcan also climb vertically or even rotate through 360°. Therefore notonly flat surfaces can be inspected, but also curved—for examplecylindrical—surfaces.

BACKGROUND ART

Thus far, robots with magnetic coupling have been fitted with wheelswhich are made, at least externally, in contact with the surface, ofpermanent magnets or electromagnets.

Prior art solutions exhibit one notable disadvantage. Whilst being ableto function, they require enormous power to drive the wheels in order toovercome the magnetic field which tends to immobilize the wheels. It istherefore difficult to achieve free-sliding movement along the surfacebeing inspected.

Moving the robot requires a powerful electric motor and therefore theneed of electrical wiring to a remote power source, making the robotheavy and cumbersome.

SUMMARY OF THE INVENTION

The Aim of this invention is to propose a mobile robot with magneticcoupling which is able to overcome, at least partially, thedisadvantages described above of the prior art robots.

This aim is achieved by a robot in accordance with claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and the advantages of the robot according to thepresent invention will appear more clearly from the followingdescription of preferred non-limiting embodiments thereof, withreference to the attached drawings, in which:

FIG. 1 shows a perspective view of a robot according to the invention;

FIG. 2 shows a perspective view of the robot from below;

FIG. 3 shows an end view of the robot;

FIG. 4 shows an exploded view of a support with permanent magnets;

FIG. 5 shows an exploded view of a robot wheel with auxiliary magnets;

FIG. 5 a shows the assembled wheel;

FIG. 6 shows an exploded view of another robot wheel;

FIG. 7 shows a perspective view of the robot frame according to onedifferent embodiment;

FIG. 8 shows an enlarged perspective view of one of the two transverseaxles supporting the frame shown in FIG. 7 and enabling it to slide overa surface to be inspected;

FIG. 9 shows a partial cross-section of the transverse axle of FIG. 8;

FIG. 9 a shows a side view of the transverse axle;

FIG. 10 shows a view of the transverse axle tilted to the horizontal;

FIG. 11 shows an exploded view of a magnet support, according to adifferent embodiment; and

FIG. 12 shows the support of FIG. 11 duly assembled.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the above figures, numeral reference 1 globallyindicates a mobile robot with magnetic coupling according to theinvention.

Robot 1 includes a frame 10 with wheels 12, 14 enabling the robot toslide over a resting surface 2 which is highly magnetically permeable,for example a ferromagnetic material. The robot 1 is in the form of amobile carriage able to move over a surface, for example a piece ofsheeting to be inspected.

In accordance with a preferred embodiment, the robot 1 is fitted with atleast one driving wheel 12 enabling independent movement over thesurface to which it is coupled magnetically. This does not exclude thepossibility of the robot described below being moved manually along theresting surface.

In accordance with a preferred embodiment, at least one driving wheel 12is powered by a motor reduction gear 16.

Advantageously, the motor reduction gear 16 is powered electrically withcontinuous voltage of, for example, 12 V, supplied by a battery 18fitted to the frame 10 of the robot 1. Therefore, the robot does notneed to be connected up to a power supply by electrical cable.

At least one wheel, for example a guided wheel 14, is connected to asteering device 20.

The robot 1 is therefore able to move forwards, backwards, to the rightand left.

According to an advantageous embodiment, these movements are controlledby a remote control handset via a CPU 22 fitted to the robot frame.

In one possible embodiment, the robot is fitted with at least onepermanent magnet 30 capable of magnetic interaction with the restingsurface 2, so as to couple the robot to said surface.

The permanent magnet 30 is fitted so as to graze the resting surface 2.In other words, the magnet 30 is detached from the ferromagnetic surface2, but is kept at a pre-set distance, able to generate a magnetic forceof attraction such as to enable the robot 1 to remain sturdily anchoredto the resting surface 2, whatever its direction or motion.

In order to maximize the density of the magnetic field acting on theresting surface 2 and therefore the force of attraction, the magnet 30is fitted with one of its poles facing the resting surface 2. In otherwords, the axis of the two poles of the magnet 30 is perpendicular tothe surface 2.

Clearly, the factors which determine the intensity of the magnetic fieldbetween the at least one magnet 30 and the resting surface 2, i.e. thedistance between the magnet and the surface, the type, shape and size ofthe magnet, will be chosen on the basis of the application, the travelof the magnet, the weight of the robot (plus any load such as a probe).

In a particularly advantageous embodiment, at least one magnet 30 isfitted onto a support 32 which is allowed to oscillate freely so thatthe magnet is always oriented in the position of minimum distance fromthe resting surface, that is in the position of maximum field density.

Preferably, magnets 30 are fitted close to the points of contact betweenthe robot 1 and the resting surface, i.e. close to the wheels 12, 14.

In the illustrated embodiment, the robot is fitted with a couple ofdriving wheels 12 and a couple of guided wheels 14.

In accordance with a preferred embodiment, the robot 1 is fitted withfour supports 32, for example comprising essentially parallelepipedblocks, each carrying several magnets 30. Each magnet is, for example,disc or tablet shaped, and has surfaces parallel to the resting surfaceof the robot. The blocks 32 are advantageously fitted to the rotatingshafts 13, 15 of the wheels 12, 14. Each block 32 is fitted with ballbearings 34 to enable free rotation around the shaft to which it isfitted. The ball bearings 34 are fitted to the support 32, for exampleby seeger 35.

In one embodiment, each magnet 30 is fixed or glued to a pillar 36,cylindrical in form for example, seated in a housing 36 inside thesupport 32 and held into place by a pin 37, for example.

In one embodiment, the magnets 30 are parallel to each other, forexample aligned parallel to the shaft 13.

In one embodiment, the permanent magnets 30 are in neodymium.

According to an advantageous embodiment, further permanent magnets 40,henceforth called supplementary magnets, are fitted into the casing 42of at least one couple of coaxial wheels, preferably the driving wheels12.

In one embodiment, these supplementary magnets 40 comprise smallcylinders which, when fitted into a wheel, turn the relevant axisparallel to the wheels axis. In a possible embodiment, the wheels 12include a central cylindrical casing 42, for example in aluminium,where, around a hole for the rotating shaft 13, a crown-shaped series ofcylindrical housings 43 is created which are fitted with cylindricalmagnets 40.

The central casing 42 is fitted between a couple of side disks 44 madeof ferromagnetic material with a milled outer surface 44 for contactwith the surface 2. Advantageously, the disks 44 are fixed to thecentral casing 42 by means of the magnetic field generated by thesupplementary magnets 40.

Around the rotating surface 42′ of the central casing 42 of the wheel 12an anti-slip fascia 45, made of rubber or similar type of material, isfitted.

The function of the supplementary magnets 40 is to generate a magneticfield interacting with the resting surface 2 of ferromagnetic material,in order to ensure that the fascia 45 always adheres to resting surface2, preferably by exerting optimum pressure on it. In this way the wheelsdo not slip on the support surface, in particular the driving wheels,even when the surface 2 is damp, for example to facilitate ultra-soundmeasurements.

Advantageously, the fascia 45 is kept in position by two side discs 44,clamping from opposite sides of the wheel.

Clearly, given its position on the wheels, the crown of supplementarymagnets 40 acts on the resting surface 2 one magnet at a time, the oneclosest to the surface as the wheel rotates. This advantageouslyproduces the desired effect of increasing the adherence of the robot tothe surface, by preventing the slippage of the wheels, withoutpreventing their proper rotation once they have made contact with theferromagnetic surface.

In terms of the structure of the wheels, the central casing 42 of thedriving wheels 12 and/or the casing 50 of the guide wheels 14 has amulti-faceted rolling surface, i.e. a polygonal shape able to improvethe anti-slip effect still further.

On the casing 50 of the guide wheels 14, for example, a tooled tyre 51can be fitted.

In accordance with the embodiment illustrated in FIGS. 7-10 and with theinvention, the robot has a frame 100 with longitudinal axle 101connecting two transverse axles 102 for the purposes of sliding alongthe ferromagnetic surface to be inspected. The longitudinal axle 101 hasan articulated joint 104 enabling the two transverse axles 102 to rotateindependently of the longitudinal axle. This enables the robot to movealong uneven or rough surfaces, for example along weld lines to bechecked, without losing adherence, as shown in FIG. 10.

In accordance with a preferred embodiment, near each wheel 107 of therobot, each axle 102 is fitted with a permanent magnet 106. The wheel107 may advantageously include supplementary magnets and/or may befitted with a tyre and/or multi-faceted rolling surface, as describedabove in relation to FIGS. 5 and 6.

Every wheel 107 is fitted to the end of a rotating shaft 108, forexample by means of a clamping pin 109. A support flange 110 for atleast a ball bearing 112 extends axially and inwardly from the wheel107. On the bearing 112 an oscillating support 114 is fitted for atleast one permanent magnet 106 coupling the robot to the restingsurface.

This support 114 has a cavity underneath where the permanent magnet 106is fitted, for example, by pressure, with one of the two opposing polesfacing the ferromagnetic surface. In accordance with one embodiment,this magnet 106 is rectangular, longer and wider than thick, and withthe largest surfaces parallel to the ferromagnetic surface. The face ofthe permanent magnet facing the sliding surface is kept at such a heightthat it grazes said surface without being in actual contact.

In accordance with a particularly advantageous embodiment, the support114 for the magnet 106 is in contact with the sliding surface via aroller 116, or preferable two rollers, for example made with ballbearings. Clearly, through this double support given by wheel 107 androllers 116, the magnet is enabled to be as close to the ferromagneticsurface as possible, without the risk of making contact.

In other words, the rollers 116 act, together with the wheel, as spacersguaranteeing a slight distance between the magnet and the ferromagneticsurface.

For the transverse axles 102 to rotate about the longitudinal axle ofthe frame whilst at the same guaranteeing that the wheels and rollersadhere to the sliding surface, the shaft 108 must be capable of tiltingin relation to the wheels 107 and the oscillating support 114 of themagnet.

For this purpose, in accordance with a particularly advantageousembodiment, the axial housing 120 for the rotating shaft 108 whichcrosses the flange 110 of the bearing support has a conical shape,widening towards the inside, allowing the shaft 108 to tilt in relationto the flange axis.

In accordance with one embodiment, the support 114 of the magnet has anaxial portion 114′ extending towards the inside, beyond the bearing, soas to house a magnet 106 which is longer than the bearing width. Aslot-shaped aperture 122 provided in said axial portion 114′ receivesthe rotating shaft 108 allowing the shaft to oscillate in relation tothe support.

In accordance with one embodiment, the end 108′ of the rotating shaft towhich the wheel 107 is fitted has a rounded outer surface, for exampleogival, so it can oscillate inside the axial hole of the wheel 107.

Advantageously, the wheel 107, flange 110 and support 114 of the magnetare clamped together along the axis by an outer washer 124, attached tothe wheel 107 and screwed tight to the end of the rotating shaft 108 andan inner washer 125, around the rotating shaft and pressed against themagnet support, for example by a spring 126.

Therefore, the wheel, flange with bearing and magnet support arepack-assembled in order to make a single wheel unit with the magnet inposition hovering over the sliding surface.

FIGS. 11 and 12 show another embodiment of an oscillating support 150for at least one magnet 152. This embodiment is particularly suitablefor applications with small diameter pipes, for example diameters ofless than meter, where the robot must be compact. A single oscillatingsupport 150, in this embodiment, is fitted centrally to at least one ofthe two rotating shafts of the wheels.

The support 150 includes a prism-shaped casing 154, with a face turnedto the sliding surface in which there is a housing 156 for at least onepermanent magnet 152, arranged, as described before, with one poleturned to the ferromagnetic surface to be inspected. Preferably, themagnet 152 is rectangular or bar-shaped and fitted horizontally, forexample, pressed into the housing 156.

Contact between the support 150 and sliding surface is by means oflateral rollers 158, for example two for each end of the support,preferably fixed to the appendices outlining the housing 156 of themagnet. These rollers 158 act as spacers similarly to the descriptionabove for the support element 114.

To provide oscillation, the support 150 is fitted to the rotating shaftby means of a couple of bearings 160, seated in respective housings 162clamped to the support casing, for example, by a seeger 163.

In accordance with an advantageous embodiment, the bearings 160 are ofthe oscillating type, in order to allow the rotating shaft, in this casetoo, to oscillate, albeit less than in the previous example with thedual oscillating support for each transverse axle.

The robot according to the invention is particularly suitable forcarrying a probe for the purposes of carrying out the non-destructivetesting of weld lines and the seal of metal plating, for example carbonsteel. In particular, the robot 1 is designed for applications involvingcylindrical sheeting (for example tanks of great length or largediameter) made by calendaring and welding flat sheeting. It should benoted that, for ultra-sound probes to work to best effect, these metalsheets need to be damp.

The robot is hooked up to the sheeting to be inspected via a permanentmagnetic field generated by magnets at some distance from the sheetingand hence without impeding the rotation of the wheels, as occurs inprior art robots. Therefore a powerful motor is not required. A smallmotor reduction gear is sufficient, powered by a 12 V battery.

The disposition of the magnets 30, 40, 106, 152 allows the robot toclimb vertically with its load, and to rotate through 180° withoutlosing adherence, even on a damp and slippery surface.

Since the robot, according to this invention, does not require powercables for its movement, data from the probes can advantageously betransmitted in wireless mode. Therefore, the robot 1 is completelyfree-standing, compact and easy to handle.

According to this invention, largely due to the reduced weight of themotor, the robot has an overall weight (including the power battery) ofless than 15 Kg, well below the regulatory maximum for weights to belifted by operators (30 kg for men, 20 kg for women).

The proposed robot is therefore very simple and easy to use andtransport.

A person skilled in the art may, according to specific needs, modify,adapt or replace some elements with others of similar or identicalfunction, without departing from the scope of the claims below. Each ofthe features described for a particular embodiment can be incorporatedirrespective of the other forms of embodiment described.

1. Robot comprising a frame fitted with wheels for movement over ahighly permeable magnetic resting surface, and with at least onepermanent magnet able to magnetically interact with said surface forcoupling the robot to the surface, characterized in that said permanentmagnet is arranged in such a way as to graze the resting surface. 2.Robot according to claim 1, wherein said at least one permanent magnetis located and held at a preset distance from the resting surface. 3.Robot according to claim 1, wherein said at least one magnet is housedin a support able to oscillate freely so that the pole of the magnet isalways oriented in the position of minimum distance from the restingsurface.
 4. Robot according to claim 1, wherein at least one permanentmagnet is located near each wheel.
 5. Robot according to claim 4, inwhich near each wheel a support is fitted to house a plurality ofpermanent magnets.
 6. Robot according to claim 5, in which saidpermanent magnets are in the form of discs or tablets with flat surfacesparallel to the resting surface.
 7. Robot according to claim 4, in whichclose to every wheel a support is fitted for housing a parallelepiped orbar-shaped magnet arranged horizontally.
 8. Robot according to claim 3,in which every support is fitted so as to oscillate on the rotationshaft of the wheels.
 9. Robot according to claim 8, in which the frameis fitted with two couples of wheels fitted to respective parallelshafts, close to each wheel an oscillating support being mounted on theshaft.
 10. Robot according to claim 3, in which each support is incontact with the support surface to be inspected via at least oneroller.
 11. Robot according to claim 1, wherein the frame comprises alongitudinal axle connecting two transverse axles enabling the robot tomove over the surface to be inspected, said longitudinal axle beingfitted with an articulated joint enabling the independent rotation ofthe two transverse axles in relation to the longitudinal axle.
 12. Robotaccording to claim 8, in which each rotation shaft is free to tilt inrelation to the wheels and the oscillating supports for the magnet. 13.Robot according to claim 12, in which each oscillating support of a pairof oscillating supports on the same transverse axle is fitted with aball bearing supported by a flange extending from a respective wheel,said flange having an axial hole through it for the rotating shaft, saidhole being conical in shape so as to allow the shaft to oscillate inrelation to the axis of the flange.
 14. Robot according to claim 13, inwhich the oscillating support has a slot-shaped aperture for theoscillation of the rotating shaft in relation to the support.
 15. Robotaccording to claim 13, in which each wheel has an axial hole into whichone end of the rotating shaft is inserted, said end having a roundedouter surface so as to oscillate inside the wheel hole.
 16. Robotaccording to claim 1, comprising a plurality of supplementary permanentmagnets fitted into at least one coaxial wheel couple.
 17. Robotaccording to claim 16, in which around each wheel having supplementarymagnets, a fascia made of anti-slip material guaranteeing adherence tothe support surface is mounted.
 18. Robot according to claim 17, inwhich said fascia is fitted between and held in place by two lateraldiscs in ferromagnetic material attracted by the supplementary magnets.19. Robot according to claim 17, in which said supplementary magnetscomprise small cylinders mounted so that their axes are parallel to thewheel axes.
 20. Robot according to claim 19, in which, in every wheel,these supplementary magnets are fitted into their cylindrical housingsin crown form in the wheel casing around a hole for the rotating shaft.21. Robot according to claim 16, in which the wheels fitted withsupplementary magnets are the driving wheels.
 22. Robot according toclaim 1, including at least one couple of driving wheels driven by amotor reduction gear powered by a continuous voltage electric batteryfitted to the frame.
 23. Robot according to claim 1, including asteering device connected to at least one wheel.
 24. Robot according toclaim 1, in which the movements of the robot are remote controlled froma handset via a CPU fitted to the frame.
 25. Robot according to claim 1,in which at least one wheel couple has a casing with a multi-facetedrolling surface, i.e. a polygonal form, to prevent slippage.
 26. Robotaccording to claim 1, including a probe to check weld lines for metalsheeting.
 27. Robot according to claim 26, in which the data picked upby the probe is transmitted to a data collection system by wireless.